The runners at the Downtown Y might be adding to their health benefits by running as a group, Dr. Alexis Stranahan says.

"He almost got kicked out of the group over those shoes," joked Eddie Butler.

The group regularly gets together to run during lunchtime and is probably getting a double benefit, according to research by a Georgia Health Sciences University neurobiologist. Exercise helps create new neurons in the adult brain in an area associated with learning, at least in animal models, and camaraderie helps ensure they get that benefit.

In research she performed at Princeton University before moving recently to Augusta, Dr. Alexis M. Stranahan found that social isolation could blunt or delay the benefits of exercise in rats.

In the study, running on a wheel raised the amount of steroid stress hormones in both grouped and isolated sets of rats. The isolated rats levels stayed elevated longer, which apparently suppressed the formation of new neurons, while the grouped rats saw new ones.

The neurotransmitter serotonin is known to be secreted by exercise and to enhance the formation of new neurons, but social isolation has been shown to decrease receptors for serotonin, which could block its effects, Stranahan said.

"The serotonin hypothesis is very interesting," she said. "If you've got serotonin but you don't have the receptor, it is like a tree falling in the forest with no one to hear it."

The new neurons appeared in an area of the brain called the dentate gyrus in the hippocampus, which has been associated with learning and memory, Stranahan said.

"More neurons in the dentate gyrus has been repeatedly correlated with enhancement of learning and memory," she said. "Conversely, suppressing the generation of new neurons in the dentate gyrus impairs learning and memory."

That social isolation would have a detrimental effect on humans and that exercise positively affects the brain has been shown by some recent studies, including one at GHSU. Dr. Catherine Davis at the Georgia Prevention Institute at GHSU published a study recently that showed increased blood flow to the brain in an area involved in executive function among sedentary kids in an exercise program, who subsequently did better on math.

Numerous epidemiological studies have paired participation in social activities with decreased rates of cognitive decline among the elderly, Stranahan said.

"Participation in church groups, participation in any kind of social group, a book club, is going to protect your neuronal function as you age, as is participation in exercise," she said.

But the two don't necessarily have to be done simultaneously, Stranahan said.

"Do I think that going for a run by yourself is bad? Of course not. I do it every day," she said. "But I do think that if you are under stressful conditions, such as those seen during depression and other psychiatric conditions, you might require a longer amount of exercise training to feel the brain-based benefits."

Sofia Verney-Carron said she used to run by herself before joining the downtown running group a year ago, at first just because she wanted the safety in numbers.

"But I really do love running with these guys," she said. "It's a good group. I would definitely miss it."